4b 



of Ca(rT03)2 gave results similar to those obtained with a 

 0.000C2m concentration of the lead salt alone. 



Combinatio:-S containing CaCNOjjg in concentrations 

 of 0.03333m, C.04ra and C.C5ra respectively, produced the 

 sqme sort of germination as was obtained with a concentra- 

 tion of 0.0C033n Pb(KC ) combined with a O.05m concentra- 

 tion of the calcivun salt; germination was practically all 

 normal, only an occasional appressorium or swelling being 

 found. 



From the above data the conclusion seems warranted 

 that the same molecular ratio of the calciim salt to that 

 of lead produces practically identical effects with the 

 three concentrations of Pb(NC3)2 here used. Concentrations 

 of O.Clm, C.C2m and O.C6m Ca(N03)2 combined, respectively, 

 with concentrations of O.CC016m, C.C0C33m and C.0C066m 

 Pb(N03)2 produce practically the same effect on spore ger- 

 mination as O.COOOSm concentration of the lead salt alone. 

 It thus appears that for ail thrse very different concen- 

 trations of Pb(NC3)2, the addition of Ca(N03)2 in the pro- 

 portion of six molecules of the calcium salt to one molec- 

 ule of Pb(KC3)2 reduces the toxicity of the latter salt to 

 a point where it almost, but not quite, inhibits normal 

 germination and nearly restricts germinal activity to the 

 formation of appressoria and other swellings. To obtain 

 this same condition of germination a simple solution of 

 Pb(N03)2 must have a concentration of O.OOCOSm. 



A similar series of equivalent effects upon spore 



